Method for centrifugal casting and apparatuses for practising it



March 23, 1965 F. TRINDLER 3,174,199

METHOD FOR CENTRIF'UGAL CASTING AND APPARATUSES FOR PRACTISING IT FiledMay ll, 1961 8 Sheets-Sheet 1 N V EN 70/? FRIEDRICH T/?/ N OLE? March23, 1965 F. TRINDLER 3,

mm'mon FOR CENTRIF'UGAL CASTING AND APPARATUSES FOR PRACTISING rr FiledMay 11, 1961 s Sheets-Sheet 2 NVENTOfi F Rl DR/CH Til/VOL ER A TTORNEYSMarch 23, 1965 F. TRINDLER 3,174,199

METHOD FOR CENTRIF'UGAL CASTING AND APPARATUSES FOR PRACTISING IT FiledMay 11, 1961 a Sheets-Sheet 4 /N VEN TOR FR/EbR/C'H TAiA/DZ En B/WWPWMATTD/IIY V March 23, 1965 F. TRINDLER 3,174,199

METHOD FOR CENTRIFUGAL CASTING AND APPARATUSES FOR FRACTISING IT FiledMay 11, 1961 8 Sheets-Sheet 5 lNvE'A Ta F P/EDIFICH TAINDLE F TTORNEYMarch 23, 1965 F. TRINDLER 3,174,199

METHOD FOR CENTRIFUGAL CASTING AND APPARATUSES FOR PRACTISING IT aSheets-Sheet 6 Filed May 11, 1961 I N v E NTOR FRIEDRICH TRINDLEIY XMzZMQLJ A T7'ORNEY! March 23, 1965 F. TRINDLER 3,174,199 7 METHOD FORCENTRIF'UGAL CASTING AND APPARATUSES FOR PRACTISING IT Filed May 11,1961 s Sheets-Sheet a FIG.8

ATTORNEYS United States Patent 3,174,199 METHOD FOR CENTUGAL CASTING ANDAPPTUSES FOR PRACTISING IT Friedrich Trindler, Bachtalstrasse I6,Ennethaden, Switzerland Filed May 11, 1961, Ser. No. 169,339 Claimspriority, application Sweden, May 11, 196%, 4,646/ 60 12 Claims. (Cl.22-65) This invention relates to a method for centrifugal casting ofmolten materials, preferably metals such as iron and steel, nonferrousmetals and metal alloys, in a twopart or multipart mould which isrotated during casting.

The method generally applied in such centrifugal casting implies that anew article cannot be cast in the mould until the next preceding articlehas set and/or cooled sufiiciently to permit lifting out of the mouldand until the mould, after opening thereof and removal of the castarticle, has again been closed to a state ready for casting. The coolingand removal of the cast article requires a relatively long time andtherefore has an inhibitory effect on the continuous casting operationand on the automatisation of the casting method.

To overcome these disadvantages it is suggested according to the presentinvention to use a method for centrifugal casting of molten materials ina two-part or multipart mould which is rotated during casting, and thismethod is characterized by carrying away the cast article, after it hasset sufliciently to permit dividing the mould, in one of said mouldparts as a support, and then assem bling a mould part identical to saidmould part with the rest of the mould to form a complete mould which isfully ready for casting of a new article while the earlier cast articlecools down in, and/or is removed from, the mould part accommodating it.While an article just cast sets to the strength necessary to permit itsremoval from the mould, further articles can thus be cast at a speeddetermined by the pouring of the material to be cast and by theoperations for separating and assembling the mould to a state ready forcasting, whereas the remaining setting and/ or the necessary cooling topermit removal of one of the articles cast from the mould does notunfavourably affect the speed at which the casting takes place. What ismore, the pouring can be done all the time at one and the same place,viz. where the rest of the mould is posi tioned, which dispenses withany transport between each pouring operation.

For practising the novel method the invention provides an apparatus forcentrifugal casting of molten material with the use of at least onetwo-part or multipart mould which is rotated during casting. Thisapparatus is characterized by the fact that two or more identical mouldparts are disposed on at least one supporting mechanism and can beassembled one at a time by said mechanism with the rest of the mould toform a complete mould fully ready for casting.

For a better understanding of the invention a number of examples will bedescribed in the following with reference to the accompanying drawingsin which:

FIG. 1 is a diagrammatic plan view of an apparatus according to theinvention;

FIG. 2 is a vertical section of the mould parts and a gripping mechanismadapted to lift the cast articles out of the mould, and diagrammaticallyillustrates different phases of the method according to the invention;

FIG. 3 is a vertical sectional View, partly in side elevation, of anembodiment of the apparatus;

FIG. 4 is a plan view of the apparatus shown in FIG. 3;

FIG. 5 is a vertical sectional view, partly in side elevation, of afurther embodiment of the apparatus;

FIG. 6 is a horizontal sectional View of the apparatus 3,174,199Patented Mar. 23, l65

ice

shown in FIG. 5, partly in section on line VI-VI in FIG. 5;

FIG. 7 is a vertical sectional view, partly in side elevation, of stillanother embodiment of the apparatus;

FIG. 8 is a side elevational view of the appanatus shown in FIG. 7.

First, the method according to the invention will be explained in moredetail with reference to the diagrammatic FIGS. 1 and 2. Mounted on theupper side of a supporting mechanism in the shape of a preferablyhorizontal disk (turntable) 10 adapted to turn about its center, arefour lower mould parts 13a-13d which are identical. The disk 10 isprovided along its periphery with a gear rim 11 which meshes with a gear12 driven by a drive motor. Each of the lower mould parts 13ad ismounted for rotation on the disk 10 and adapted to be rotated by anindividual drive mechanism. By intermittent rotation of the disk 10 insteps of each, the four lower mould parts 13a-d are movable in turn oforder to four different stations designated 1-1! in FIGS. 1 and 2. Whenso moved the mould parts can be brought in position directly beneath anupper mould part 14 (FIG. 2) located in station I and mounted forrotation above the disk 10. The upper mould part 14 is preferablydisposed in a frame (not shown) and rotatable by an individual drive. Toassemble the mould part 14 with that mould part (FIG. 1) which isbeneath it, to form a complete mould ready for casting, the disk 10 withthe mould parts 13ad thereon or the mould part 14 can be axiallyshiftzable. Means (not shown) are arranged above the mould part 14 forpouring molten material into the closed mould in station I. A grippingmechanism 15 (FIG. 2) is disposed in station IV above the disk 10 toremove the finished castings from the mould, and said mechanism iscarried by a supporting device (not shown) by means of which it isshiftable to a position beyond the periphery of the disk 14 above aconveyor (roller track) 16. The gripping mechanism may, however, also bestationary and there may be provided one or more means to move thecastings from the gripping mechanism to a hot working station or atransit store.

With the disk 10 in the position shown in FIG. 1 the mould part 13a andthe mould part 14a are situated opposite one another and can thereforebe closed to form a mould ready for casting. The mould is now caused torotate, if this has not been done already before the closing of themould, and material to be cast is poured into the mould while it isrotating. After the material poured into the mould has set suiiicientlyin order not to be thrown out of the mould when this is opened the mouldparts 13a and 14 can be slowly separated whereupon the casting(designated 17 in all occurrences in FIGS. 1 and 2) is moved, whilelying in the mould part 13a which is still held in rotation, fromstation I to station II by a rotation of the disk 10 through an angleequal to 90. By this rotation of the disk 10 the mould part 13a issimultaneously moved from station IV to station I and beneath the uppermould part 14 while the casting 17 in station II further sets and/ orobtains so high a strength that it may then be removed from the mould.In this way a new casting can simultaneously be cast in the mould formedby the mould parts 13d and 14 in station I. The procedure is repeated,the mould parts Ilia-d being advanced one step at a time correspondingto an angle of 90, and material to be cast is poured into the mould instation I during the stop period of the disk 10 between any tworotational steps. The castings 17 made in station I eventually arrive instation IV where they are removed from the corresponding lower mouldpart by means of the gripping mechanism 15 and are deposited for exampleon the conveyor 16 to be transported to other working stations.

For an optimum capacity of the casting apparatus the 5. number of mouldparts on the disk can be selected in such a way that the time allowingthe casting to set sufficiently and to be removed from the mould islonger than the time required forthe operations in-station I up tothe'pouring of material to be cast into the mould. If the settingtime issay 120 seconds-and theoperations in station I (closing'themold, pouringthe material to be cast, opening the mould and supplying a new mouldpart)take 40 seconds, there are thus required three steps for thesuccessively set and/orreach-the'strength required for removing themfrom the mould. The fact that the mould parts are permanently held inrotation eliminates the time and energy losses which derive from arepeated braking and-acelerationof the mould parts. Therefore the gripping mechanism 15 also must be arranged in such a way as torotatesynchronously with the rotating-mould parts and that the grippingof the casting can take place at the same speed,.in order that thecasting may be removed from the mould.

The method according to the invention naturally is not bound to thespecial arrangment diagrammatically shown in FIGS. 1 and 2, but canbepractised with apparatuses of different design It should be mentionedspecifically that the rotary disk can be replaced by one or more othermeans for transporting the. lower mould parts between thedifferentstations, such as swingarrns, slides or carriages whichareguided on rails in a closed-circuit. In addition to the station in whichthe material to be cast is poured into the mould, and the stations inwhich'the casting cools down, up to the station in which the finishedcasting is lifted out of, or discharged from, the mould there may bearranged one or more stations'in which the mould parts are subjected topreliminary treatments, such as application of silicates, orprovided-with prefabricated insets of refractory material or the like.Moreover, the axes of rotation of the mould parts may be arrangedhorizontally or in any position of inclination whatever between thevertical position'shown and horizontal position.

A structural embodiment of the apparatus outlined above in connectionwith the explanation-of the method according to the invention will nowbe described in more detail with reference-to FIGS. 3 and 4 in thedrawings.

The apparatus shown therein is arranged in a chamber 29 for instance ofconcrete and comprises a rotary disk 21 which. is centrally mounted on averticalupright 22 in said chamber for both rotational movement andshifting movement in the axial sense. For rotation of the rotary diskthe latter is provided witha peripheral gear rim 23 which meshes with agear 25 driven by a motor 24, alid for raising the rotary disk 21 singleacting hydrauliccylinders 26 with piston rods 27 aremounted on the floorof the chamber 20, while lowering of the rotary'disk is brought about byits own weight. The gear 25 is of so large an axial length as to remainin mesh with the gear rim 23 in all height positions of the rotary disk21.

A number of mould carriers for carrying lower mould FIGS, 3 and rier 28,and possibly to such mould carriers as may be arranged additionally. Themould carrier 28 is mounted for rotation by means of ball bearings 30 ona bushing 29 rigidly connected to the rotary disk 21. It is operativelyconnected over a drive belt 31 to a drive motor 32 on the rotary disk 21and is braked by means of a brake belt 34. The drive belt 31 and thebrake belt 34 act on a downwardly directed shell portion 33 of the mouldcarrier 28. The brake belt 34 has one 'endsecured in a fastening 35arranged in fixed position on the rotary disk 21, and its other'endsecured between the ends of a lever arm 36, which is mountedfor swingingmovement on the rotary disk 21* in a point 37 at its one end, while itis operable at its otherend by means of a hydraulic cylinder 38 which isprovided in the manner of a link between the last mentioned end of thelever arm 36 and a fixed point 39 on therotary disk 21. A circular'annular lower mould part '40 is attached to the mould carrier 23;Disposed at the periphery of the'mould carrier 28 is a number of springs28a which serve to elastically centerthe mould by means of'screws 28b! Aflange sleeve 41is arranged in the upper portion of the chamber 20, andan upper mould carrier 42 is rotatably'mounted on saidsleeve'41'by'means of'b'all bearings 43. Said mould carrier 42 has anupwardly directed shell portion 44 about which there are passed a belt45'for driving the mould' carrier 42 and a brake belt 46 for braking it.The drive belt and the brake belt can be operatively connected with amotor and a brake applying device, respectively,-in themanne'rfshown forthe'mould carrier 28, with the difierencdhowever, that the motor and thebrake applying device 'for mould carrier 42 of course are stationarilymounted in thechamber 20, for instance at the underside of the upperwall thereof instead of being disposed on the rotary disk 21, as shownfor mold carrier 28. A circular annular uppermould part 47 'is arrangedbeneath the upper mould'carrier 42,

and by raising the rotary disk 21 by means of the cylinders 26 saidmould'part 47 can be closed against the mould part 40 to form amouldready for casting, when 7 part dii'according to FIG' 3 is directlybeneath part 47.

In the same manner the mould part 40" and further lower mould parts,'ifany, can be caused to close separately against the mould part 47 toform-a mould ready for easting, as said lower mould parts arealternately movable into position beneath the mould part 47. Theembodiment'in FIG. 3 is intended for water-cooled upper mould parts.with a water chamber 47:: and is fixedly connected to the mould carrier42 via an annular intermediate portion 4715-61. The intermediateportion-is a flange with an upwardly tapering shell 47 b which via ribs47c isintegral with an inner portion 47d and is fixedly connected-to'themould carrier 42 so that the waterchamber 47a can be supplied withcooling medium through the annular space between 475 and 47d also duringthe rotation of the mould;

Cooling medium is poured onto the conical surface 47d by a pipe (notshown)-rrom where the medium flows into the cooling medium chamber 47a.

To prevent the cooling'medium from splashing upon rotation of the moldthe supply conduit 47c is conical and 'wide'ns in a downward direction.Whenthe mold is stationary or slowly rotating the cooling-medium flowsonly over the conical surface 47d. At a higherrotational' speed of themold it is possible that cooling medium-will be thrown away from thesurface 47d and becaught by the tapering shell 4712] In the interior ofthe mould carrier 42 there is provided a supply pipe 48 lined withrefractory material and rotatably mounted on the flangesleeve 41 bymeans of ball bearings 49 and 50. The pipe 48 is fixedly connected .to apulley 51 which is drivable by means of a belt 52 from a drive motor 53.The pulley 51 is formed with an upwardly directcd flange54about'which'is passed a brake belt 55 which is applied by means'of abrake applying device 56in the same manner as the abovementioned brakebelt 34. The mouth end 57 of thesup- In this instance the mould part 47is equippedply pipe 48 is bent in one direction in the peripheral sense,preferably in the direction opposed to the intended direction ofrotation of the mould and the supply pipe in order that a calm flow ofthe melt into the mould may be obtained. However, the mouth may also bearranged more or less radially, and instead of being rotatable thesupply pipe may naturally be stationary.

The upper end of the supply pipe 48 constitutes a continuous connectionto a ladle 59 on the chamber 20 and is spaced a slight distance from theoutlet opening 58. Naturally this outlet opening may be located in aholding furnace or melting furnace. To protect the jet of castingmaterial between the ladle 59 and the pipe 43 from atmosphericinfluences there is arranged a cover 60 between the ladle 59 and thepulley 51, said cover having a sealing device 61 to the ladle 59 and asealing device 61a to the pulley 51. Also provided in the cover 69 is apassage 62 through which a protective gas can be supplied, protectingthe melt against oxidation, or through which passage evacuation can beeffected. However, the melt can be protected against oxidation also bymeans of a gas screen in and per se known manner. The flange sleeve 41contains a passage 63a for supplying cooling medium to the chamber 63band 63c between the relatively movable parts 41, 42, 48. For the samepurpose fan blades may quite as well be provided at the outlet openingson top of the pulley 51 or at the underside of the support of the supplypipe 48. The supply pipe 48 has a further pipe 65 attached to andsupported on its lower portion, the pipe 15 at 66 being in communicationthrough a small slot with the pipe 67 to supply covering material orreagent. The closed mould parts 40 and 47 may be provided through thissupply means with a coating before casting is done.

The connection at 66 is of such a known type that the pipe 65 isrotatable together with the supply pipe 48 relative to the pipe 67disposed on the mould carrier 28. The pipe 67 is automatically separatedfrom or connected to the pipe 65 at 66 when the mould carrier 28 withthe bushing 29 on the rotary disk 21 moves to open and close the mould40, 47, respectively. At the lower end of the pipe 67 there is provideda supply passage 682 in which is disposed a slide 68c movable by acylinder 68a via a piston rod 68b for supplying predetermined quantitiesof material, for instance covering material, in the pipe 67. Thismaterial can then be conveyed, for instance by means of a compressed airpulse in a manner similar to that in pneumatic dispatch tubes, from acompressed air supply (not visible behind rotary disk 21) through asupply pipe 68d and through the pipes 65 and 67 into the cavity of themould formed by the mould parts 40 and 47.

A gripping mechanism for lifting the rings R cast in the apparatus outof the moulds and carrying them away from the apparatus is mounted abovethe lower mould carrier 28' and the lower mould part 40' carriedthereby. The gripping mechanism is carried in its entirety by a slide 70which is disposed in a guide 71 in the upper portion of the chamber 20for movement in the horizontal sense. A hydraulic cylinder 72 for movingthe slide 70 is arranged as a link between the slide and a fixedabutment 73 in the chamber 20. The supporting device of the grippingmechanism is a turntable 74 which is mounted for rotation in the slide70 by means of a sleeve 75 and aball bearing 76. Passed about a flange77 on the turntable 74 are a drive belt 78 for rotating the turntable 74from a drive motor 79 on the slide 70, and a brake belt 80 which isfixedly anchored to the slide 81 and can be applied against the flange77 by means of a hydraulic brake applying device 82 of substantially thesame design as the earlier described brake applying device 36-39.Gripping jaws 84 are secured to a number of radially placed pull rods 83each having a three-pronged fork, more precisely to the prong ends ofsaid fork. At the underside of the turntable 74 the pull rods 83 areeach guided in one guide 85 and have each of their prongs in a guide 86.Each pull rod 83 is provided at its end closest to the center of theturntable 74 with rotatably mounted rollers 37 which are inserted inT-grooves 88 in a conical clamping head 89'. This head has at its upperportion a stem 89 which is movable in the sleeve 75. The stem 89 isoperatively connected to the piston rod of a hydraulic cylinder 90 foraxially moving the head 39. As is readily seen, an axial movement of thehead 89 results in a simultaneous shifting of the gripping jaws 84radially in that said jaws are moved outwards at the downward shiftingof the head and inwards at the upward shifting of the head. In thepresent instance the gripping jaws 84 are moved inwards to cause them togrip a ring R lying in the lower mould part 40, and outwards to depositan earlier gripped ring. These functions, however, are also conceivablein the reverse direction. When the lower mould part 40' is in the raisedposition shown the gripping mechanism can thus be caused to grip thering R, and after the lower mould part 40' has again been lowered, thegripped ring by a movement of the slide 7 0 can be brought outside ofthe assembly formed by the rotary disk 21, the lower mould carriers andthe lower mould parts to be deposited on a suitable conveyor outside thechamber 20 or to be transported to a working station.

Each of the mould carriers on the rotary disk 21 is enclosed by acylindrical shell; two of said shells are shown in the drawing anddesignated 91 and 91'. These shells are arranged and designed in thesame manner, and the following description of one shell 91 thereforeapplies also to the other. The shell 91 is carried by uprights 92 andbrackets 93 on the rotary disk 21. On its inner side the shell has acircular cooling medium conduit 94. Along said conduit there is provideda number of openings 95 which are directed radially towards the jointbetween the mould parts 40 and 47 when the mould is closed. The conduit94 is connected to a supply line, preferably for air under pressure, ina manner not shown. When the lower mould part 40 is closed against theupper mould part 47 cooling medium can be supplied in the mannerindicated, preferably after the beginning of the casting operation, tothe joint between the two mould parts for cooling of the mould and then,after the casting has obtained sufficient strength so that absolutely nomelt is thrown out of the mould, for a controlled cooling of the castingin that the mould parts 40 and 47 are slightly separated while coolingmedium is blown through the joint between the mould parts towards thecasting. For the rest the mould parts may be bevelled at the outer edgesof their facing surfaces, as is shown at 96 and 97, in order that thecooling medium supplied may be pressed in better between the mouldparts. After the mould parts 40 and 47 have been further separatedcooling medium can still be supplied to the cast article lying in thelower mould part.

The apparatus shown in FIGS. 5 and 6 is adapted for casting segmental orcircular castings. This embodiment of the invention includes a rotarytubular shaft on which there is arranged a pair of diametrically opposedsupport arms 126 and 126' which are axially movable on the shaft 125 bymeans of a pair of hydraulic cylinders 127 which are disposed eachbetween one abutment 128 secured to the shaft 125 and the correspondingsupport arm. The support arm 126 carries a mould carrier 134) rotatablymounted by means of ball bearings 129, and a lower mould part 131mounted on said mould carrier. The other support arm 126' is arranged ina corresponding manner so that the mould parts carried by the supportarms can be caused to change places in the same way as was described inconnection with the preceding embodiment, for which reason it will notbe described in more detail here. The lower mould part 131 is closedagainst an upper mould part 132 carried by an upper mould carrier 133which is rotatably mounted on a stationary bushing 134 in the mannerearlier described and is driven 7 by means of a belt 135 and braked bymeans of a brake belt'136. The two mould parts 131 and 132 can bepressed against each otheralon'g a separating line 137 by means of thecylinders 127.- A supply pipe 138likewise in a manner earlierdescribed-4s rotatably mounted in the bushing 134 and in the uppermouldcarrier 133 and is driven by a belt'139. This supply'pipe' 138 dividesitself into two mouth portions 140a and-140b situated at the same leveland directed radially outwards from the supply pipe, whereby theirmouths, in the closed position of the mould parts, lie inside the mouldcavity formed by the mould parts. The supply pipe'138 is rotatable notonly by means of the belt139 but also by means'of the upper mouldcarrier 133, which is provided witha pivotally mounted spring loadedpawl1'41which' engages'one carried along by the mouldcarrier' 133 driven bythe belt 135, and the resultant rotary movement of the mould carrier 133is assumed to take place, in the embodiment shown, in a clockwisedirection as seen in FIG. 6. In the interior of the mouldcavity thereare arranged on the inner side 'of'the wall of the lower mould part 131a pair of diametrically opposed rib-shaped projections 143a and 143bwhich extend over the entire axial length of said wall. The notches142aand 14% are so arranged relative to said rib-shaped projections'143aand 1431) that the mouths of the two branches 140a and 140b, when thepawl 141 engages in one of said notches, are positioned at one of theprojections 143a and 1431; in order that the pouring of the melt intothe mould-shall start at one projection and be terminated'at the otherprojection.

At the use of this apparatus the mould is first closed and then theupper mould carrier 133 and the upper mould part 132 carried thereby arecaused to rotate by means of the belt 135, the lower mould part 131 andthe lower mould carrier- 130 being carried along in the rotation by thefrictional engagement between the mould parts along .the separating line137 while the supply pipe 138 is carried along in the rotation by meansof the pawl 141 which is in engagement with one of the notches 142a and142i).

After the suitable number of revolutions has been reached for the mouldand the supply pipe 138 the latter is given a slightly higher speed thanthe mould at the moment when the melt flows into the mould in that saidpipe is rotated by means of the belt 139 so, that the mouths of thebranches 140a and 14% move along an arc of a circle between the twoprojections 143a and 143b, whereby a semi-circular arc profile'or asemi-circular mouldingis cast between the two projections 143a and 14311on either side thereof. It is obvious that a relative movement betweenthe mould and the supply pipe can be realized in a manner. other thanthat shown here and that this relative movement can be produced byincreasing or reducing the speed of rotation of the mould or the supplypipe.

The embodiment according to FIGS. 5 and 6 can be modified for thecasting of two rings. In such a case two annular cavities, one above theother, are arranged in the lower mould part 131 and in accordancetherewith the mouth portio'ns14ila and 14 3b are disposed at dilferentlevels so that the material to be cast can'fiow' into each of the twoannular cavities. The apparatus is used in the same manner as theapparatus according to FIGS. 3 and 4, but two rings are cast at the sametime The apparatus according to FIGS. 7 and 8 includes an upper mouldcarrier 156 which is rotatably'mounted on a stationary bushing 155 andcarries an upper mould part 157. Adapted for cooperation with this uppermould part is an intermediate mould part 158 which is rotatably mountedin a water film produced in a jacket 159. Said jacket is carried by arotary disk 160 which is disposed on a tubular shaft 161 and is axiallymovable. rotary disk carries a number of furtherinterrnediate mouldparts which are identical with the intermediate mould part The B 153'andone of which is shown at 158. The apparatus further includes a lowermould part 162 which is attached to a mould carrier 162 which is mountedfor rotation in a support arm 164 by means of ball bearings 163. Thesupport arm 164' is integral with a sleeve 165 which is axially movablebut non-rotatable on thetubular shaft 161, whereas the rotary disk isfixedly attached to the tubular shaft 161 and mounted for rotation. Toraise and lower the unit formed by the support arm 164and the sleeve apair of hydraulic cylinders 167" is arranged between said unit and astationary abutment 166. A core 168 is movable in the interior of thelower mould part 162 in such a way that in the operative position of theapparatus it extends with its upper end into the cavity formed by themould parts, but is withdrawable from said cavity by axial displacement.A hydraulic cylinder 169 is adapted to displace the core 168. Thiscylinder is carried by a member 176 extending from and integral with thesleeve 165. The core 168 is mounted for rotation on the piston rod 172of the hydraulic cylinder 169 by means of ball bearings 171. It ishollow and an' axially disposed pipe 173 for supplying cooling medium tothe interior of the core projects into the hollow thereof. The differentmould parts can be rotated and braked in analogy to what has beendescribed earlier. The core 168 is coupled to the lower mould part 162by means of a wedge 168 which permits the core to' be axially displacedrelative to the lower mould part.

The embodiment in FIGS; 7 and 8 also exemplifies the use of looseinserts in the mould, which may present cooling apertures. Such aninsert, for instance a silicate insert, is located in the upper portionof the intermediate mould part 158 at 174. This insert has a supplypassage 176 connected to the supply pipe 175 of the mould. Such insertsmay of course be used in different designs and in different Ways and mayconsist of different materials. In connection with this embodiment itshould also be mentioned that the inserts may consist of a number oflamellar elements which are provided with mould cavities at theirperiphery and are withdrawable fromthe mould cavity for instance also inthe course of the casting operation.

The embodiments described above and shown in the drawing may of coursebe modified according to the object contemplated, and the structuraldetails shown here may of course easily be assembled to othercombinations than those shown here. Therefore, the invention is notlimited to what is shown in the drawings and described in thespecification but covers all conceivable modifica-' tions within thespirit and scope of the appended claims.

What I claim is:

1. A method of centrifugal casting of rings having round orpolygonal'profiles with rounded outer edges, comprising bringingtogether the parts of a multi-part mold having at least an upper partand a lower part and being rotatable in a horizontal plane, casting aring in the mold by inserting a supply pipe into the mold, rotating themold, rotating the supply pipe in synchronism with one point on the molduntil the time at which the molten metal starts to flow through thesupply pipe into the mold, flowing molten metal through the supply pipeinto the mold, rotating the pipe relative to the mold during the flow ofmolten metal into the mold until the molten metal has flowed into all ofthe parts o f the circumference of the mold, and after the casting hassolidified sufiiciently, separating the mold parts, carryiug away thecasting in the lower mold part which serves as a support, and moving afurther mold part identical with that carried away together with theremaining upper mold part to complete a further mold ready for casting anew article, and cooling the casting previously cast in the carried-awaymold part and withdrawing the cooled casting from said carried-away moldpart.

2. A method as claimed in claim 1 in which the molten metal isdischarged from the pipe in the direction opposite to the direction inwhich the pipe is rotated, whereby the molten metal is relatively gentlydeposited in the mold while the mold and the supply pipe are rotating atrelatively rapid speeds.

3. A method as claimed in claim 1 in which the molten metal isdischarged from the pipe in a direction circumferentially of the mold,and the mold and the supply pipe are driven at angular speeds whichdiffer from each other only slightly, whereby the molten metal leavingthe supply pipe will have a speed approximately zero with respect to themold.

4. A method as claimed in claim 1 further comprising the step of placinga covering material over the molten metal in the mold immediately afterflow of the molten metal into the mold has ended.

5. An apparatus for centrifugal casting of rings having round orpolygonal profiles with rounded outer edges, comprising a plurality oflower mold parts each of which is identical with the other lower moldparts, a carrying device rotatable about a vertical axis and on whichsaid lower mold parts are rotatably mounted at intervals around saidcarrying device for rotation about vertical axes, an upper mold partrotatably mounted for rotation around a vertical axis and positionedabove one of the lower mold parts on said carrying device and beneathwhich the other lower mold'parts are moved when said carrying device isrotated, raising means on said carrying device for raising said lowermold parts into engagement with said upper mold part to form a completemold, mold rotating means connected to said mold parts for rotating themabout their vertical axes, a supply pipe extending through the uppermold part along the vertical axis thereof and mounted for rotation aboutsaid vertical axis, said supply pipe extending into the mold formed bythe upper mold part and a lower mold part and laterally of said axis toa point adjacent the periphery of said mold, and supply pipe drive meansconnected to said supply pipe for rotating said supply pipe about said3X15.

6. An apparatus as claimed in claim 5 in which the end of said supplypipe with in the mold extends parallel to the direction of movement ofthe end of the pipe and opens in the direction opposite to the directionof rotation of the pipe.

7. An apparatus as claimed in claim 5 and pawl means coupling said uppermold part and said supply pipe for driving said supply pipe at a speedequal to the speed of the upper mold part, whereby the supply pipe isdriven at the same speed as the mold, and when pouring of the moltenmetal into the mold is started, the supply pipe can be dniven at agreater speed than the speed of the mold.

8. An apparatus as claimed in claim 5 further comprising a continuousclosed metal supply system adapted to extend from a means for holdingmolten metal and connected to said supply pipe for keeping the moltenmetal out of contact with the atmosphere.

9. An apparatus as claimed in claim 8 in which said apparatus has asealing means around the end of said supply pipe adapted to be sealed toa means for holding molten metal, said apparatus having a gas inletthrough said sealing means for admitting a protective gas into saidsupply pipe for protecting the molten metal from the atmosphere.

10. An apparatus as claimed in claim 5 and a protective gas supply pipeattached to the said molten metal supply pipe within the mold having anoutlet end extending laterally of the mold to a point adjacent theperiphery of the mold, the inlet end of the said protective gas supplypipe extending through the lower mold part along the vertical axis ofrotation thereof, and a protective gas supply coupled to the lower endof said protective gas supply pipe.

11. An apparatus as claimed in claim 10 in which said protective gassupply pipe is in two parts, an upper part secured to said molten metalsupply pipe and a lower part extending through each lower mold part,said upper and lower pipe parts engaging with each other when a lowermold part is moved into engagement with said upper mold part.

12. A method of centrifugal casting of rings having round or polygonalprofiles with rounded outer edges, comprising bringing together theparts of a multi-part mold having at least an upper part and a lowerpart and being rotatable in a horizontal plane, casting the ring in themold and rotating the mold during casting, while casting and rotatingthe mold, protecting the molten material from the atmosphere bysupplying protective gas to the interior of the mold and directlyagainst the cast material immediately after it has been poured into themold, and after the casting has solidified sufficiently, separating themold parts, carrying away the casting in the lower mold part whichserves as a support, and moving a further mold part identical with thatcarried away together with the remaining upper mold part to complete afurther mold ready for casting a new article, and cooling the castingpreviously cast in the carried-away mold part and withdrawing the cooledcasting from said carried-away mold part.

References Cited by the Examiner UNITED STATES PATENTS Re. 24,827 5/60Lasater et a1 2265 1,634,914 7/27 Reichold 2265 X 1,721,115 7/29Harrington 2277 1,885,465 11/32 Moulton 2277 1,908,607 5/ 33 Hokin 22652,023,040 12/35 Adams 2265 2,570,325 10/51 Dalton 2265 2,681,485 6/54Smith 22215 2,829,408 4/58 Shuck 2265 2,966,709 1/ 61 Ruppel et a1 2277X MICHAEL V. BRINDISI, Primary Examiner.

MARCUS U. LYONS, WINSTON A. DOUGLASS,

Examiners.

5. AN APPARATUS FOR CENTRIUGAL CASTING OF RINGS HAVING ROUND ORPOLYGONAL PROFILES WITH ROUNDED OUTER EDGES, COMPRISING A PLURLAITY OFLOWER MOLD PARTS EACH OF WHICH IS INDENTICAL WITH THE OTHER LOWER MOLDPARTS, A CARRYING DEVICE ROTATABLE ABOUT A VERTICAL AXIS AND AN WHICHSAID LOWER MOLD PARTS ARE ROTATABLY MOUNTED AT INTERVALS AROUND SAIDCARRYING DEVICE FOR ROTATION ABOUT VERTICAL AXES, AN UPPER MOLD PARTROTATABLY MOUNTED FOR ROTATION AROUND A VERTICAL AXIS AND POSITONEDABOVE ONE OF THE LOWER MOLD PARTS ON SAID CARRYING DEVICE AND BENEATHWHICH THE OTHER LOWER MOLD PARTS ARE MOVED WHEN SAID CARRYING DEVICE ISROTATED, RAISING MEANS ON SAID CARRYING DEVICE FOR RAISING SAID LOWERMOLD PARTS INTO ENGAGEMENT WITH SAID UPPER MOLD PART OT FORM A COMPLETEMOLD, MOLD ROTATING MEANS CONNECTED TO SAID MOLD PARTS FOR ROTATING THEMABOUT THEIR VERTICAL AXES, A SUPPLY PIPE EXTENDING THROUGH THE UPPERMOLD PART ALONG THE VERTICAL AXIS THEREOF AND MOUNTED FOR ROTATION ABOUTSAID VERTICAL AXIS, SAID SUPPLY PIPE EXTENDING INTO THE MOLD FORMED BYTHE UPPER MOLD PART AND A LOWER MOLD PART AND LATERALLY OF SAID AXIS TOA POINT ADJACENT THE PERIPHERY OF SAID MOLD, AND SUPPLY PIPE DRIVE MEANSCONNECTED TO SAID SUPPLY PIPE FOR ROTATING SAID SUPPLY PIPE ABOUT SAIDAXIS.